Impacts of Fire on Butterfly Genetic Diversity and Connectivity

How do novel fire regimes and a long history of fire suppression influence species genetic diversity? Genetic diversity provides the raw materials for sustaining viable populations and for allowing adaptation to novel environmental challenges, and at present, few studies address the genetic responses of animals to fire management. Here we study the genetic responses of 2 butterfly species to a landscape gradient of fire timing and severity in Yosemite National Park using a large set of genome-wide single nucleotide polymorphisms (SNPs). Butterflies are important bio-indicators of invertebrate diversity and play important roles in both bottom-up and top-down ecosystem processes, and typically increase in abundance following wildfires, due to an increase in abundance of flowering plants. However, it is not clear how genetic diversity and genetic connectivity of butterflies respond to landscape change following fire, and whether fire management has positive or negative effects. We found evidence to suggest that fire increases genetic diversity and reduces isolation in 2 butterfly species, but that aspects of the fire regime (severity, extent, timing, and frequency) differ in importance depending on the ecology of the specific species. This research is the first study to address fire management impacts on genetic diversity in invertebrates, and the results will allow fire managers to predict that fire reintroduction in protected areas will generally benefit butterfly populations.